Ultraviolet absorbents with a benzophenone skeleton have conventionally been used as compounding agents in the medical and cosmetic fields, or as additives for various plastics. As, however, the dispersivity and solubility of these absorbents in substrates were poor, there was a limit to their blending proportion, and bleeding also occurred due to the low stability of the dispersions. Further, although silicone oils are used in many different fields, benzophenone compounds were particularly difficult to dissolve in silicone oils.
To overcome these disadvantages, benzophenone skeletons have been introduced into polysiloxane molecules by converting compounds having such a skeleton to alkyl ether derivatives with hydrolyzable groups such as alkoxysilyl, making use of the phenolic hydroxyl group, and hydrolyzing them together with chlorosilanes or alkoxysilanes (Japanese Patent Kokai (Unexamined Published Japanese Patents) 21432/'82, 10591/'83, 213075/'83, 11130/'86 and 187740/'87).
Benzophenone skeletons have been introduced into polysiloxane molecules also by reacting isocyanates with hydrolysable groups such as alkoxysilyl together with the phenolic hydroxyl groups of compounds having such a skeleton so as to obtain carbamoyloxy derivatives, and then hydrolyzing them together with chlorosilanes or alkoxysilanes (Japanese Patent Kokai 21390/'82).
In both of these methods, however, as the derivatives with a benzophenone skeleton have an alkoxysilyl group, they also tend to be hydrolyzed when used in admixture with polysiloxanes which have no reactive functional groups, and their stability is poor. In particular, when these compounds with hydrolyzable groups are used in medical or cosmetic preparations, there is a further problem in that the substances produced by hydrolysis cause irritation to the skin and mucous membranes.
Although the use of silicone oils in medical and cosmetic preparations has been increasing in recent years, a compound with a benzophenone skeleton which not only was very soluble in silicone oils, but which also did not have hydrolyzable groups and was therefore stable, had not yet been obtained.
The inventors of the present invention, after various experiments, discovered that by introducing non-reactive organosilicon or organopolysiloxane groups into the benzophenone skeleton, the product obtained had excellent solubility in substrates and especially silicone oils, and thereby arrived at the present invention.